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C H A P T E R 7
P a g e 7 . 6
G e t t i n g
S t a r t e d
used the correct presentation. Try re-analysing the measurement data with a new
presentation.
Á The statistics of the distribution are calculated from the results using the
derived diameters D[m,n] - an internationally agreed method of defining the
mean and other moments of particle size. See British standards BS2955:1993 for
more details.
D(v, 0.5), D(v, 0.1) and D(v, 0.9) are standard "percentile" readings from the
analysis.
. D(v, 0.5) is the size of particle at which 50% of the sample is smaller and
50% is larger than this size. This value is also known as the Mass median di-
ameter (MMD).
. D(v, 0.1) is the size of particle for which 10% of the sample is below this
size.
. D(v, 0.9) gives a size of particle for which 90% of the sample is below this
size.
 D[4,3] is the volume mean diameter.
à D[3,2] is the surface area mean diameter. Also known as the Sauter mean.
Ä Span is the measurement of the width of the distribution. The smaller the
value the narrower the distribution. The width is calculated as:
b g b g
−
d
0 9
.
d
01
.
b g
d
0 5
.
Å Concentration. This is the volume concentration. It is calculated from the
Beer-Lambert law and is expressed as a percentage.
Æ Distribution. This tells you the type of distribution the analysis has used. The
options for this is set in the Result modification dialogue in the Setup menu.
Options include change from volume to surface area, length or number. It must
be remembered that the Mastersizer measurement is fundamentally a volume
distribution - transforming the result into a surface, length or number
distribution is a mathematical process that may amplify any error in the original
result.
Ç Obscuration. The obscuration helps set the concentration of the sample when
it is added to the dispersant. It is a measure of the amount of laser light lost due to
the introduction of the sample within the analyser beam. An ideal range is
between 10 and 30%.
È Uniformity. The uniformity is a measure of the absolute deviation from the
median.
M A N
0 1 0 1
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